Ankle joint for artificial limbs



. 24, 1940. s. H JETER 2,215,525

ANKLE JOINT FUR ARTIFICIAL LIMBS Filed March 12, 1958 27 25 h f 4 24 A? Patented Sept. 24, 1940 UNITED STATES PATENT" OFFICE 3 Claims.

This invention relates to the class of artificial body members and pertains particularly to improvements in ankle joints for artificial limbs.

In the ankle joints used at the present time 5-- in artificial limbs, two pivotal points are made use of whereby forward and rearward motion and lateral motion may take place and the lateral movement permitted by such joints is relatively small.

l The present invention has for its primary object to provide an improved ankle joint unit which permits the" user of the artificial limb to have a substantial amount of lateral motion 7 I without bringing the parts of the shank and foot 15 of the artificial limb into contact.

Another object of the inventionis to provide an improved artificial limb ankle joint wherein novel bearing units are provided which permits of the free forward and rearward swaying of the shank 2!). of the limb and a relatively wide range of swaying movement of the shank laterally with respect to the underlying foot.

The invention will be best understood from a consideration of the following detailed descrip- 25, tion taken in connection with the accompanying drawing with the understanding that the invention is not confined to any strict conformity with the showing of the drawing, but may be changed or modified so long as such changes or modificam tions mark no material departure from the salient features of the invention as expressed in the appended claims.

In the drawing: Figure 1 is a view in vertical section through 35 the length of a foot and the lower portion of the shank of an artificial limb showing the joint embodying the present invention.

Figure 2 is a section taken on the line 22 of Figure 1. Figure 3 is a section taken on the line 33 of Figure 2.

Referring now more particularly to the drawing wherein like numerals of reference designate corresponding parts in the several views, the numeral l designates an artificial foot while the shank coupled therewith is indicated by the numeral 2. This foot I is shown as having a top recess 3 in which a lower part of the shank positions as illustrated, and bears against a suit- 50 able soft rubber cushion insert 4. These details of construction are illustrated and described merely for the purpose of setting forth the application of the joint embodying the present invention and do not in themselves constitute any 55 part of the invention.

The joint structure embodying the present invention comprises a body 5 which is here illustrated as being in the form of a cylinder so that this body is thus provided with a transversely rounded top surface which is indicated by the 5 numeral 6 and which constitutes a bearing surface as will hereinafter be more specifically described together with the function thereof. This cylinder body 5 is mounted in the center part of the recess 3 to extend transversely of the foot on 10 a line which would be occupied by the ankle joint of a natural foot.

Suitable means is provided for maintaining the cylinder body 5 fixed in-position, and such means is here shown as consisting of a pair of inserts l placed within the body 5 and each provided with a suitable threaded aperture or passage 8 to receive the threaded end of a steel securing pin 9 which is extended upwardly through a suitable aperture in the body of the foot l and through a suitable opening in the:cylinder 5, as shown in detail in Figure 2. Such securing pins 9 have retaining nuts Ill threaded upon their lower ends, which nuts position in a suitable recess H on the underside of the foot.

Within the cylinder body 5 is positioned between the inserts 'l, the cylindrical bearing 52 which is provided with a downwardly directed transverse recess I3 which coincides with a similar recess M formed through the body 5 as shown in Figure 2.

Extending transversely through the cylinder body 5 upon the longitudinal center thereof and positioned in the recesses |3-M, is a pivot bar l5which constitutes the yoke portion which connects the sides or legs I6 of a U-bolt which is designated as a whole by the numeral II. This U- bolt has its leg portions l5 disposed in a plane extending longitudinally of the foot l, and these legs extend upwardly through the lower part of 40 the shank 2 and terminate in the chambered area i8 where they receive the securing nuts l9 by which the pivot bar forming the yoke portion I5 is drawn tightly upwardly into the bight of the recesses I3I4.

Encircling the cylindrical body is a metallic bushing 20 which is provided with a suitable transverse recess 2| which corresponds with the recesses l3-l l, and which has the pivot bar l5 extended therethrough. One end of this bushing 29 is undercut as indicated at 22 to form a shoulder which bears against one inclined side of a rib 23 which partially encircles the body 5. This bushing 20 is, as shown in Figure 2, disposed between the securing pins 9, and its ends are suitably notched or cut out to permit a partial rotation of the bushing without interference from the pins.

Disposed upon the top of the cylindrical body 5 and extending longitudinally of the same between the legs I6 of the U-bolt, is a supporting bearing which is generally designated by the numeral 24. This bearing has a long transversely arched bearing surface which rests against the top bearing surface 6 of the body 5 so that the bearing 24 may oscillate on the surface 6 in the natural forward and backward swaying movement of the shank 2 when the limb parts are in motion as in walking.

The top of the bearing 24 is longitudinally arched, forming the arched bearing surface 26 which engages a corresponding bearing face 21 formed in the lower part or end of the shank 2 between the legs I6 of the U-bolt ll. These bearing surfaces 26 and 2! have relative motion when the shank 2 moves laterally with respect to the foot. The arched surface 26 of the bearing 24 has a center rib 28 extending throughout its length for engagement in a corresponding channel or groove in the bearing face 2'! whereby relative side movement of the bearing and the shank is prevented.

By providing the bushing 20 with the undercut shoulder 22 and the cylinder 5 with the rib 23 against which the shoulder bears, side play of the bushing is prevented when the shank 2 is tilted to the side or in a movement corresponding with the bending of the ankle laterally.

From the foregoing it will be readily apparent that with the improved ankle joint herein disclosed, the shank 2 will not only be permitted free forward and rear swaying motion relative to the foot part I, but may have considerable freedom of lateral movement, and these desirable results are obtained without a multiplication of joint parts and without sacrificing strength. This ankle joint differs from those at present in use in the important fact that only one center or pivot is made use of for both backward and forward movement and for lateral movement also.

What I claim is:

1. An ankle joint coupling between the shank and foot of an artificial limb, comprising a cylinder disposed transversely of the foot between the same and the shank and secured against rotation, a pivot bar extending transversely of the cylinder in a transverse slot therein and through the axial center thereof, means securing the bar to the shank, the bar forming a pivot for the lateral swaying of the shank, means facilitating rocking of the bar on an axis transverse to its long axis for the forward and rear swaying of the shank, and a supporting bearing for the shank between the same and the cylinder facilitating free forward, rearward and lateral swaying of the shank relative to the foot.

2. An ankle joint coupling between the shank and foot of an artificial limb, comprising an elongated body disposed to extend transversely of the foot between the latter and the shank and having a transversely rounded top bearing face, said body having a slot cut transversely therein, on a line with the longitudinal center of the foot, said slot extending above the longitudinal center of the body, means at opposite sides of said slot for securing the same to the foot, a bearing body within said first body between the said securing means and having a transverse slot aligning with the slot of the first body, a bar extending through said alined slots and directed longitudinally of the foot, the center of said bar being in intersecting relation with the radial center of the rounded bearing face of the first body, said bar being adapted to have rotation on its long axis in said alined slots and oscillation on an axis perpendicular to its long axis, the said bearing body oscillating with the bar within the first-mentioned body, means securing said bar at its two ends with the shank, and a bearing resting upon the rounded bearing face of said first body and supporting the said shank on the first body whereby the shank is permitted oscillatory movement in a plane extending longitudinally of the first body and in a plane extending transversely thereof.

3. An ankle joint coupling between the shank and foot of an artificial limb, comprising a cylinder disposed between the shank and foot and extending transversely of the foot, the top surface of said cylinder constituting a bearing face, said cylinder having a slot cut transversely therethrough from the lower side to beyond the longitudinal center thereof, the slot extending through the cylinder on the longitudinal center of the foot, means securing the cylinder at opposite sides of the slot to the foot, a bearing lying within the cylinder between the said securing means and having a transverse recess alining with said slot, means securing the cylinder to the shank comprising a substantially U-shaped bolt having a straight bar portion forming a yoke which extends through the alined slot and recess of the cylinder and bearing, and the said bar intersecting the longitudinal center of the cylinder and being rockable on its long axis in the bearing recess and the slot and oscillatable on an axis transversely to its long axis with the bearing, and a supporting bearing block interposed between the top of said cylinder and said shank, said last bearing block being in the form of a segment of a disk having a transversely concaved edge extending longitudinally of and resting upon the top of the cylinder and having a longitudinally arcuate edge upon which a correspondingly formed part of the shank rests for oscillatory movement, the said arcuate edge being concentric with the axis of said bar.

SINCLAIR H. JETER. 

